Stream: git-wasmtime

Topic: wasmtime / PR #11304 Allow compiling debug-builtins in no...

Wasmtime GitHub notifications bot (Jul 22 2025 at 19:32):

dblnz opened PR #11304 from dblnz:no-std-debug-builtins to bytecodealliance:main:

Description

This PR takes care of enabling the compilation of gdb_jit_int module in the jit-debug crate to ensure the native debugging also works in no_std environments.

The

This work has been discussed in #wasmtime > Debugging a wasm module in a hyperlight guest.

Summary

• Make jit-debug crate #![no_std] when perf_jitdebug is not enabled
• Make gdb_jit_int module build in no_std environment
• Use std when perf_jitdebug is enabled because the perf_jitdebug module does not run in no_std environment
• Split debug-builtins feature into debug-builtins and perf-builtins to individually toggle:
  - the no_std gdb_jit_int module by using debug-builtins
  - the std perf_jitdebug module using perf-builtins. NOTE: They can be both enabled, but it won't support no_std.

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Wasmtime GitHub notifications bot (Jul 22 2025 at 19:32):

dblnz requested alexcrichton for a review on PR #11304.

Wasmtime GitHub notifications bot (Jul 22 2025 at 19:32):

dblnz requested wasmtime-core-reviewers for a review on PR #11304.

Wasmtime GitHub notifications bot (Jul 22 2025 at 19:32):

dblnz requested wasmtime-default-reviewers for a review on PR #11304.

Wasmtime GitHub notifications bot (Jul 22 2025 at 19:55):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 22 2025 at 21:03):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Jul 22 2025 at 21:03):

alexcrichton created PR review comment:

I forget how we ended up at the organization

Wasmtime GitHub notifications bot (Jul 22 2025 at 21:03):

alexcrichton edited PR review comment.

Wasmtime GitHub notifications bot (Jul 22 2025 at 21:03):

alexcrichton edited PR review comment.

Wasmtime GitHub notifications bot (Jul 22 2025 at 21:04):

alexcrichton edited PR review comment.

Wasmtime GitHub notifications bot (Jul 23 2025 at 12:04):

dblnz edited PR #11304:

Description

This PR takes care of enabling the compilation of gdb_jit_int module in the jit-debug crate to ensure the native debugging also works in no_std environments.

My aim is to have this in for the LTS version 36.0.0 :smiley:

This work has been discussed in #wasmtime > Debugging a wasm module in a hyperlight guest.

Summary

• Make jit-debug crate #![no_std] when perf_jitdebug is not enabled
• Make gdb_jit_int module build in no_std environment
• Use std when perf_jitdebug is enabled because the perf_jitdebug module does not run in no_std environment
• Split debug-builtins feature into debug-builtins and perf-builtins to individually toggle:
  - the no_std gdb_jit_int module by using debug-builtins
  - the std perf_jitdebug module using perf-builtins. NOTE: They can be both enabled, but it won't support no_std.

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  conversation. If it was discussed in an issue, just mention "issue #...".

• Explain why this change is needed. If the details are in an issue already,
  this can be brief.

Our development process is documented in the Wasmtime book:
https://docs.wasmtime.dev/contributing-development-process.html

Please ensure all communication follows the code of conduct:
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Wasmtime GitHub notifications bot (Jul 23 2025 at 17:27):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Jul 23 2025 at 17:27):

alexcrichton created PR review comment:

Can this condition be massaged a bit to still include the has_host_compiler_backend conditional somehow? (or something like that)

Previously it was a nice property that compiling Wasmtime to an unknown/unsupported platform wouldn't involve compiling any C code and I'd ideally like to preserve that. An example situation where C code is not needed is a platform using Pulley even when debug-builtins is enabled because in such a situation the builtins aren't actually used by anything.

Wasmtime GitHub notifications bot (Jul 23 2025 at 17:27):

alexcrichton created PR review comment:

This unfortunately is a dependency we cannot use. Spinning on contention is almost never the right concurrency primitive as it's only particularly useful in a kernel setting when interrupts are disabled for example. I also unfortunately do not have a great answer of what to do as an alternative. The best I can think of is "panic on contention" in no_std mode but still use a real std::sync::Mutex in std mode.

Wasmtime GitHub notifications bot (Jul 23 2025 at 17:27):

alexcrichton created PR review comment:

I think it'd be best to skip this feature and have this force-enabled as part of the profiling feature, this separate feature doesn't actually enable anything otherwise in Wasmtime itself

Wasmtime GitHub notifications bot (Jul 23 2025 at 19:08):

dblnz submitted PR review.

Wasmtime GitHub notifications bot (Jul 23 2025 at 19:08):

dblnz created PR review comment:

Ok, thanks for the comment. I wasn't sure what the right decision was here.
I think panic in no_std mode should be fine

Wasmtime GitHub notifications bot (Jul 23 2025 at 19:09):

dblnz edited PR review comment.

Wasmtime GitHub notifications bot (Jul 23 2025 at 19:27):

dblnz submitted PR review.

Wasmtime GitHub notifications bot (Jul 23 2025 at 19:27):

dblnz created PR review comment:

Hmm, I see, I followed the debug-builtins feature and noticed it depends on some symbols from the C, and I thought that for debug-builtins this will be needed.
I'll have another look

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:07):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:21):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:25):

dblnz submitted PR review.

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:25):

dblnz created PR review comment:

The idea I had in mind was that before this change, debug-builtins also enabled the perf_jitdump, so when compiling wasmtime-cli and providing --features debug-builtins now it won't enable the perf_jitdump anymore.
I had added a perf-builtins so that this option could be enabled from the wasmtime-cli.

I have taken your advice and force-enabled perf_jitdump as part of profiling. Let me know if you'd like to change

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:30):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 24 2025 at 23:36):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 25 2025 at 12:27):

dblnz requested alexcrichton for a review on PR #11304.

Wasmtime GitHub notifications bot (Jul 25 2025 at 18:19):

alexcrichton updated PR #11304.

Wasmtime GitHub notifications bot (Jul 25 2025 at 18:20):

alexcrichton commented on PR #11304:

I've pushed a few commits as feedback here. Mind double-checking them and confirming they're ok for you?

Wasmtime GitHub notifications bot (Jul 28 2025 at 13:17):

dblnz commented on PR #11304:

I've pushed a few commits as feedback here. Mind double-checking them and confirming they're ok for you?

It looks good from my point of view.

Nice touch with the use of optional feature enablement.

"wasmtime-jit-debug?/std",

Wasmtime GitHub notifications bot (Jul 28 2025 at 13:56):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Jul 29 2025 at 17:16):

dblnz updated PR #11304.

Wasmtime GitHub notifications bot (Jul 29 2025 at 20:47):

alexcrichton merged PR #11304.

Last updated: Dec 06 2025 at 06:05 UTC